MINERALOGY: R. A. DALY 
663 
clumps and lenticular masses of similar, minute crystals of orthoclase, 
which are interlocked and thus without crystal form (see fig. 7 of the 
writer's memoir). The clumps and lenses of feldspars regularly enclose 
many rhombohedra of dolomite. Occasionally in thin section one sees 
entire laminae, up to 1 or 2 mm. in thickness, composed of about equal 
parts of orthoclase and dolomite. The feldspar is clearly not of clastic 
origin. 
Analysis of the rock gave the following result, which has been thor- 
oughly checked, the alkalies being subjected to four closely accordant 
determinations by two different analysts. 
Si02 30.46 K20 5.77 
AI2O3 6.86 H20 1.42 
FeaOs 4.53 CO2 22.55 
FeO 1.89 
MgO 10.07 99.95 
CaO 16.02 Sp.gr 2.749 
NaaO 0.38 
The estimated composition of the rock (assuming the iron oxides to 
represent magnetite) is, by weight: 
The albite is probably in solid solution with the orthoclase. So far 
as known by published analysis no other non-metamorphosed dolomite 
or limestone even approaches the Waterton dolomite in its abundance 
of the alkalies; feldspar makes up about 40% of its volume. 
When reporting on this singular rock the writer was not aware of the 
relevant observations of Lory, Foullon, Cayeux, and others. In 1912 
the dolomite remained frankly a puzzle. The theoretical conclusions of 
Heim, Triimpy, and Foullon are therefore of value in suggesting a par- 
tial explanation of the still unique American rock. The Alberta forma- 
tion differs from the European analogues in having a dolomitic base and 
in failing to exhibit good crystal form for the feldspar. This anhedral 
character may be connected with the specially high proportion of ortho- 
clase, the numerous little crystals interfering with one another as they 
grew in the calcareous mud. The writer has not the slightest doubt as 
to the chemical origin of the carbonate material nor as to the authigenic 
nature of the orthoclase; he is inchned to refer the crystallization of the 
feldspar to the early period when the sediment was not yet consoli- 
dated nor deeply buried. 
per cent 
per cent 
. 21.2 
28.6 
Orthoclase 
Albite 
Quartz . . . . 
Magnetite . 
34.5 
3.1 
6.0 
6.3 
MgCOj 
CaCOa 
99.7 
